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  Electrical machine with double-sided rotorUSPTO Application #: 20070281558Title: Electrical machine with double-sided rotor Abstract: A machine useful for ship propulsion purposes include a double-sided generator or motor with two concentric air gaps. In one embodiment, the machine includes a double-sided rotor with an inner rotor side and an outer rotor side; and a stator with an inner stator core and an outer stator core, wherein the double-sided rotor is concentrically disposed between the inner stator core and the outer stator core. (end of abstract)
Agent: General Electric Co. Global Patent Operation - Wilton, CT, US Inventors: Patrick Lee Jansen, James Michael Fogarty, Ralph James Carl, James Patrick Francis Lyons, Ronghai Qu USPTO Applicaton #: 20070281558 - Class: 440006000 (USPTO) Related Patent Categories: Marine Propulsion, Electric Drive For Propelling Means The Patent Description & Claims data below is from USPTO Patent Application 20070281558. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation in part of U.S. patent application Ser. No. 10/882,911, entitled "Electrical Machine With Double-Sided Rotor", now U.S. Pat. No. ______ which is herein incorporated by reference. BACKGROUND OF THE INVENTION [0002] The present invention relates generally to electrical machines and more specifically to wind turbine generators and ship propulsion motors. [0003] Wind is usually considered to be a form of solar energy. Wind is caused by the uneven heating of the atmosphere by the sun, the irregularities of the earth's surface, and rotation of the earth, and wind flow patterns are modified by the earth's terrain, bodies of water, and vegetation. The terms wind energy or wind power describe the process by which the wind is used to generate mechanical power or electricity. [0004] Typically, wind turbines are used to convert the kinetic energy in the wind into mechanical power. This mechanical power may be used for specific tasks (such as grinding grain or pumping water) or a generator may convert this mechanical power into electricity. A wind turbine usually includes an aerodynamic mechanism for converting the movement of air into a mechanical motion which is then converted with a generator into electrical power. Power output from the generator is approximately proportional to the cube of the wind speed. As wind speed doubles, the capacity of wind generators increases almost eightfold. [0005] The majority of commercially available wind turbines utilize geared drive trains to connect the turbine blades to the wind generators. The wind turns the turbine blades, which spin a shaft, which feeds into a gear-box and then connects to a wind generator and makes electricity. The geared drive aims to increase the velocity of the mechanical motion. The drawback of a geared drive is that it reduces the reliability of the wind turbine and increases the noise and cost of the wind turbine. [0006] A few wind turbines utilizing direct-drive generators are also commercially available. The large diameters of direct drive generators present formidable transportation and assembly challenges, both at the factories and at the wind turbine installation site. As the wind turbine industry matures and technology improves, larger power ratings will be required to continue the downward push in the cost of energy. Standard power ratings for land based turbines are expected to push to more than 3 MW in the next few years, and the offshore turbines are expected to be 5 MW or greater. [0007] For the wind turbines and ship propulsion motors to evolve to higher power ratings, conventional approaches increase the direct-drive generator diameter or axial (stack) length. Increasing the diameter is preferred from a purely generator electromagnetic perspective, but is not attractive from the transportation, frame, and assembly perspective, especially for land-based turbines. Increasing the axial length of the generators, while maintaining the diameter to be less than approximately 4.1-4.3 meters, alleviates the land-based transportation issue, but results in complex and costly frame structures with long axial extents which presents a problem in that there is a limited amount of space available on board a ship. Also this also presents a problem of increased weight that reduces the efficiency of the motor in propelling a ship. [0008] It is therefore desirable to provide cost-effective electrical machines of increased power ratings and reduced diameters. BRIEF DESCRIPTION OF THE INVENTION [0009] In accordance with another embodiment of the present invention, a ship propulsion motor is provided. The ship propulsion motor includes at lease two concentric air gaps. The motor comprises at least one double-sided rotor with an inner rotor side and an outer rotor side, and at least one stator with an inner stator core and an outer stator core. The at least one double-sided rotor is concentrically disposed between the inner stator core and the outer stator core. BRIEF DESCRIPTION OF THE DRAWINGS [0010] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: [0011] FIG. 1 illustrates a sectional view of a wind turbine comprising an exemplary double-sided generator; [0012] FIG. 2 illustrates a sectional view of the exemplary generator of FIG. 1 with a double-sided rotor and a stator; [0013] FIG. 3 illustrates a three-dimensional view of the double-sided rotor and stator of FIG. 2. [0014] FIG. 4 illustrates an exemplary embodiment with a heat pipe and an outer cooling channel in the arrangement of FIG. 2; [0015] FIG. 5 illustrates a sectional view of a portion of a ship comprising an exemplary double-sided ship propulsion motor; [0016] FIG. 6 illustrates a section view of the exemplary motor of FIG. 5; and [0017] FIG. 7 illustrates an exemplary embodiment with the gear box used with the double-sided generator of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION [0018] The present invention includes different embodiments for double-sided generators and motors that are particularly useful for direct-drive wind turbines and ship propulsion units. Additionally these embodiments may be beneficial for some geared electrical machines. The different configurations described herein below are based upon a double-sided radial-flux, synchronous electrical machines. Although permanent magnet (PM) machines are described and shown for purposes of illustration, other electrical machines such as wound field machines can alternatively be used. These configurations contribute towards achieving cost-effective wind turbines of increased power ratings (>2.0 MW) and are especially advantageous for land-based applications where the outside diameter may be constrained by transportation limitations. [0019] Turning now to the figures, FIG. 1 is a diagrammatic representation of a sectional view of a wind turbine 10 with an exemplary embodiment of a direct-drive double-sided PM generator 12. The PM generator 12 of the wind turbine 10 includes at least two concentric air gaps (not shown in FIG. 1 and discussed later in reference to FIG. 2), thereby effectively converting the PM generator 12 into two concentric generators. Thus, it would be appreciated by those skilled in the art that for the same total envelope defined by the outside diameter and the axial length, the PM generator 12 can produce considerably more power output than a single-sided generator. In practice, thus a 2 MW single-sided generator might be replaced by a double-sided generator capable of producing 3-3.6 MW for the same total diameter and axial length. Equivalently, a 3 MW single-sided PM generator having a diameter of 6 meters might be replaced with a double-sided generator of the same axial length with only 4.3 meters diameter, thereby enabling land-transportation of the entire generator as one unit. Continue reading... Full patent description for Electrical machine with double-sided rotor Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Electrical machine with double-sided rotor patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Electrical machine with double-sided rotor or other areas of interest. ### Previous Patent Application: Power system for watercraft Next Patent Application: Amphibious recreational vessel Industry Class: Marine propulsion ### FreshPatents.com Support Thank you for viewing the Electrical machine with double-sided rotor patent info. 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